def from_bytes(cidbytes):
"""
Creates a CID object from a encoded form
:param bytes cidbytes: can be
- base58-encoded multihash
- multihash
- multibase-encoded multihash
:return: a CID object
:rtype: :py:class:`cid.CIDv0` or :py:class:`cid.CIDv1`
:raises: `ValueError` if the base58-encoded string is not a valid string
"""
if multibase.is_encoded(cidbytes):
# if the bytestream is multibase encoded
cid = multibase.decode(cidbytes)
data = cid[1:]
version = int(cid[0])
codec = multicodec.get_codec(data)
multihash = multicodec.remove_prefix(data)
elif cidbytes[0] in (b'0', b'1'):
# if the bytestream is a CID
version = cidbytes[0]
data = cidbytes[1:]
codec = multicodec.get_codec(data)
multihash = multicodec.remove_prefix(data)
else:
# otherwise its just base58-encoded multihash
try:
version = 0
codec = CIDv0.CODEC
multihash = base58.b58decode(cidbytes)
except ValueError:
raise ValueError(
'multihash is not a valid base58 encoded multihash')
try:
mh.decode(multihash)
except ValueError:
raise
return make_cid(version, codec, multihash)
def test_decode_incorrect_encoding(encoded_data):
with pytest.raises(ValueError) as excinfo:
decode(encoded_data)
assert 'Can not determine encoding' in str(excinfo.value)
def test_decode(_, data, encoded_data):
assert decode(encoded_data) == ensure_bytes(data)
